Lingyun Dai

Lingyun Dai

Hunan University
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Lingyun Dai has a total of 1000 co-authors. Here are the top co-authors by number of shared publications:

Latest Publications

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    Hadronic vacuum polarization and light-by-light scattering in representative infrared-improved soft-wall holographic QCD models

    by Jin-Yang Shen, Wen-Yuan Peng, Ling-Yun Dai, Zhen Fang

    We investigate the hadronic contributions to the anomalous magnetic moment of the muon $$a_\mu $$ a μ in three representative infrared-improved soft-wall anti-de Sitter (AdS)/quantum chromodynamics (QCD) models, focusing on the leading-order hadronic vacuum polarization (LO-HVP) and hadronic light-by-light (HLbL) contributions. The model parameters are fixed by the ground-state $$\rho $$ ρ -meson mass, pion mass, and pion decay constant, with the low-lying excited spectrum used as an additional phenomenological constraint. We find that the LO-HVP contribution remains below dispersive determinations, mainly because the $$\rho $$ ρ -meson decay constant is underestimated. In the HLbL sector, the standard Chern–Simons term gives well-defined ground-state pseudoscalar-pole contributions but leads to divergent excited-state sums in soft-wall models. We therefore also adopt a scalar-extended Chern–Simons term motivated by brane–antibrane construction, which provides infrared suppression and allows finite estimates for pseudoscalar excitations and axial-vector mesons. The resulting HLbL predictions are internally convergent but still quantitatively model-dependent, showing that further refinement of the infrared completion and short-distance constraints is required.

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    Study of transition form factors of the lightest pseudoscalars

    by Yi-Hao Zhang, Shao-Zhou Jiang, Ling-Yun Dai

    In this paper, we study the transition form factors (TFFs) of the lightest pseudoscalar mesons, π 0 , η , and η ′ , within the framework of resonance chiral theory. Our analysis is performed based on the data of time-like and space-like singly-virtual and space-like doubly-virtual form factors, as well as the relevant cross sections and latest invariant mass spectra of e + e − pair for the process of P → γ e + e − . The TFFs of these pseudoscalars are obtained. Also, we evaluate their contributions to the light-by-light part of the anomalous magnetic moment of the muon. Our two fits give similar results, where the better fit (Fit-A) gives a μ π 0 = ( 61.6 ± 1.8 ) × 10 − 11 , a μ η = ( 15.2 ± 1.7 ) × 10 − 11 , a μ η ′ = ( 16.0 ± 1.2 ) × 10 − 11 , and the total contribution of neutral pseudoscalar meson poles is a μ π 0 + η + η ′ = ( 92.8 ± 2.9 ) × 10 − 11 .

    Cited by 1
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    Measurement of CP asymmetries in $ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $ and $ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $ decays

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    A bstract: Measurements of the combined CP asymmetries in $$ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $$ B ¯ 0 → D s − D + and $$ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $$ B ¯ s 0 → D s − D − decays are made using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . The measurements are found to be $$ {\displaystyle \begin{array}{l}{A}_{CP}\left({\overline{B}}^0\to {D}_s^{-}{D}^{+}\right)=0.0009\pm 0.0053\pm 0.0040,\\ {}{A}_{CP}\left({\overline{B}}_s^0\to {D}_s^{-}{D}^{-}\right)=0.103\pm 0.053\pm 0.010,\end{array}} $$ A CP B ¯ 0 → D s − D + = 0.0009 ± 0.0053 ± 0.0040 , A CP B ¯ s 0 → D s − D − = 0.103 ± 0.053 ± 0.010 , where the first and second uncertainties are statistical and systematic, respectively. This is the first measurement of this asymmetry in $$ {\overline{B}}_s^0 $$ B ¯ s 0 decays, and the most precise measurement to date for $$ {\overline{B}}^0 $$ B ¯ 0 decays. Both measurements are found to be consistent with CP symmetry.

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    Machine learning techniques for jet reconstruction at LHCb and application to the search for $ H\to b\overline{b} $ and $ H\to c\overline{c} $ in $ \sqrt{s}=13 $ TeV pp collisions

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    A bstract: Two machine learning techniques for jet measurements at the LHCb experiment are presented: a regression-based method for jet-energy calibration and a deep neural network algorithm for jet flavour tagging, distinguishing between b -quark, c -quark, and light parton jets. These techniques are applied to a search for inclusive $$ H\to b\overline{b} $$ H → b b ¯ and $$ H\to c\overline{c} $$ H → c c ¯ decays using a LHCb dataset corresponding to an integrated luminosity of 1.6 fb − 1 . The observed (expected) 95% confidence level upper limits correspond to 6.6 (11.1) times the SM cross-section for the $$ H\to b\overline{b} $$ H → b b ¯ process, and 1003 (1834) times the SM cross-section for the $$ H\to c\overline{c} $$ H → c c ¯ process.

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    Improved branching-fraction measurements of $ {B}_{(s)}^0\to {K}_{\mathrm{S}}^0{h}^{+}h{\prime}^{-} $ decays and first observation of $ {B}_s^0\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, et al.

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    Erratum: Measurement of CP asymmetry in $ {D}^0\to {K}_{\textrm{S}}^0{K}_{\textrm{S}}^0 $ decays with the LHCb Run 3 detector

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

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    Amplitude analysis of $B^0 \rightarrow \eta _c(1S) K^+ \pi ^- $ decays

    by R. Aaij, A.S.W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    An amplitude analysis of the $${{{B} ^0} \!\rightarrow {\eta _{c}} (1S) {{K} ^+} {{\pi } ^-}} $$ B 0 → η c ( 1 S ) K + π - decays with $${\eta _{c}} (1S) \rightarrow {p} {\overline{{p}}} $$ η c ( 1 S ) → p p ¯ is performed using a sample corresponding to an integrated luminosity of 9 $$\,\text {fb} ^{-1}$$ fb - 1 of $$p $$ p $$p $$ p collision data collected by the LHCb detector at centre-of-mass energies of $$\sqrt{s}$$ s = 7, 8 and 13 $$\,\text {Te\hspace{-1.00006pt}V}$$ Te V . The data are described with a model including only intermediate contributions from known $${K} ^{*0}$$ K ∗ 0 resonances. Evidence for an exotic resonance in the $${\eta _{c}} (1S) {{\pi } ^-} $$ η c ( 1 S ) π - system, reported in a previous analysis of this decay channel, is not confirmed. The inclusive branching fraction of the $${{B} ^0} \rightarrow {\eta _{c}} (1S) {{K} ^+} {{\pi } ^-} $$ B 0 → η c ( 1 S ) K + π - decays is measured to be $$\begin{aligned}&\mathcal {B}({{B} ^0} \rightarrow {\eta _{c}} (1S) {{K} ^+} {{\pi } ^-}) \\&\quad = (5.82 \pm 0.20 \pm 0.23 \pm 0.55) \times 10^{-4}, \end{aligned}$$ B ( B 0 → η c ( 1 S ) K + π - ) = ( 5.82 ± 0.20 ± 0.23 ± 0.55 ) × 10 - 4 , where the first uncertainty is statistical, the second systematic, and the third arises from the limited knowledge of external branching fractions.

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    Search for lepton-number-violating B − → D ( * ) + μ − μ − decays

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    A search is performed for lepton-number-violating B − → D ( * ) + μ − μ − decays, using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb − 1 . No significant signal is observed, and upper limits are set on the branching fractions, B ( B − → D + μ − μ − ) < 4.6 × 10 − 8 and B ( B − → D * + μ − μ − ) < 5.9 × 10 − 8 , at the 95% confidence level.

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    Differential decay rate of B+ → J/ψK+ with the LHCb Upgrade I experiment

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    A bstract: The normalised decay rate of B + → J/ψ (→ μ + μ − ) K + is measured as a function of the lepton helicity angle using a data sample corresponding to an integrated luminosity of 1 . 1 fb − 1 collected during October 2024 with the upgraded (Upgrade I) LHCb detector. This angular distribution can be parameterised by two coefficients, the forward-backward asymmetry, A FB , and the flatness parameter, F H , whose values are constrained by conservation of angular momentum. These coefficients are measured both integrated and differentially across various kinematic and detector-response variables, and the results are found to be in good agreement with expectations. These measurements show that the detector response of the LHCb Upgrade I experiment is understood to the precision required to reliably extract the angular coefficients associated with rare b → sμ + μ − and b → dμ + μ − transitions, which are particularly sensitive to physics beyond the Standard Model.

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    Branching fraction measurement of the $ \Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu } $ decay

    by R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, et al.

    A bstract: A measurement of the branching fraction for the decay $$ \Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu } $$ Λ → p μ − ν ¯ μ is presented using pp collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV. The analysis is based on data recorded between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb − 1 . The result is obtained using Λ → pμ − decays as a normalisation channel. The measured branching fraction is $$ \mathcal{B}\left(\Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu}\right)=\left(1.462\pm 0.016\pm 0.100\pm 0.011\right)\times {10}^{-4} $$ B Λ → p μ − ν ¯ μ = 1.462 ± 0.016 ± 0.100 ± 0.011 × 10 − 4 , where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalisation mode branching fraction, respectively. This result improves the precision of the branching fraction measurement by a factor of two compared to the previous best measurement and sets a more stringent bound on lepton flavour universality in s → u quark transitions. It is consistent with previous measurements, and the extracted lepton flavour universality test observable, $$ {R}^{\mu e}=\frac{\Gamma \left(\Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu}\right)}{\Gamma \left(\Lambda \to p{e}^{-}{\overline{\nu}}_e\right)}=0.175\pm 0.012 $$ R μe = Γ Λ → p μ − ν ¯ μ Γ Λ → p e − ν ¯ e = 0.175 ± 0.012 , agrees with the Standard Model prediction.

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